Process for polymerizing isoprene with a catalyst consisting of titanium tetrachloride and an aluminum hydride



United States Patent O 3,311,604 PROCESS FOR POLYMERIZING ISOPRENE WITH A CATALYST CONSHSTING OF TITANIUM TET- RACHLOREDE AND AN ALUMINUM HYDRIDE 3,3 llfifi l Patented Mar. 28, 1967 'ice Walter Marconi and Alessandro Mazzei, Milan, Marcello 5 portance for the stereospecificity of the reaction. When de Malde, San Donato Milanese, and Salvatore CllClthe ratio is between 0.25 and 1.4, expressed as a ratio be- Bella, y, asslgflol's t SNAM -P- v a tween gram atoms of aluminum and titanium, there is P 0 Y obtained prevailingly 1,4 trans polyisoprene.

i iz g is ggf g g s i g g g h ii i g i" By increasing the value of the above ratio there occurs 6 S 299 182 Pp 1O a-prevailing formation of poly-isoprene 1,4-cis. The opti- Claims priority, application Italy, Feb. 4, 1961, 1,984/61, mum value the formatlon of pq pr Patent 647,780; Nov. 21, 1961, 18,075/61, Patent higher values of the ram Al/Tl the Yleld of 707,662; Nov. 24, 1961, 21,200/ 61 1,4-c1s p'oly-isoprene decreases.

4 Claims. (Cl. 260-94.3) The polymerization is carried out in inert solvent, for This application is a division of US. patent application 15 fi tolilen or Xylane at Oidmary pressing a d Ser. No. 169,621, filed Jan. 29, 1962, and 110W abandoned. f 'ffi g i g 09 This invention relates to the stereospecific polymeriza- 3 y .atweengi T 6 {ion of isoprenei 1115111011 0 ti Ie1: reaction to 0 tain p0 ymerization 1s nor- The Production those stereospacific POIYIPBTS of 20 T-lie l lh wing e r ramples illustrate the nature of the inisoprene which are synthetic elastomers 1s of considerable vention industrial interest. Particularly interesting is the preparation of those polymers which are substantially of 1,4-c1s Examples 1 and 1,4-trans configuration, or in which such a configuration predominates. 2 I

5 n the following examples there is employed a catalyst Vanous catalytic systems have been proposed for use S p ystem for the polymerization of isoprene formed of l 0 nc ivnhitgie 52041322811111 {pail liteggolsietiilsicopolygtlgg m i (:Zfigfra A11 N((;)H )1 anfd2'(1;( )Cl 1-w1th various Al/ T1 mlclflar ndatios. 7 nto a ott e o m capacity prev1ous.y eate at a 22 igi g g j g g g z iggg g e ii y 5 2 5 21? free flame and allowed to cool down in a nitrogen stream, 1. t l riodic Table according to Mendeleieff and an aluminum i g i are mtmduced benzene and the needed amount of alkyl. Aft'e r that char e there is introduced while stirring the The object of the present invention 15 a process for the e needed amount of a benzenic solution at known concenproductfim (tat POlYlSQgFH of 1,4 configuration which is tration of dimethybaminmalanel fi y S ifi invention is based on the The bottle is sealed with a neoprene seal and a corona use of a g ifl y ti system? consisting of; type bottle cap which is punched in such a Way as to ex- (21) Titanium tetrachloride pose part of the neoprene seal.

(b) An aluminum hydride having the general formula h h bottle is held for about 10 minutes over a r U shaking stirrer at room temperature to complete the re- AlH X, wherein X is a member chosen from the roup 40 f0 batween'the catal St com Onent consisting .of hydrogen, halogen, aminic nitrogen and g g isoprene is z y yp i' Syrin e and 't en formin art of an ethero-atom 9 iogen and m fog P the bottle is put at once into a rotating thermostatic bath uch hydrides may be complexed with compounds dofor the desired length of f norsof electrons such as amines, ether, etc. At the end of that penod the content of the bottle is Examples of such catalysts are: discharged into about one litre of methyl alcohol con- H H H taining 1% of antioxidant. The precipitated polymer is dried in an oven under A1H APE AFR vacuum at room temperature, then the yield of polymer more), N (Cum): N\ /CH: is calculated. The conditions of polymerization and the OHPCH, results of the infrared analyses, are reported in the follow- AlH201.N(C2H5)I 111% Table TABLE 1 LR. Anal ses, percent A1H2N(CH.1)2, T1014, Molar BSolvent Isoprene, T 00 lgure- Yield,t y I??? I on, or n Example are as gr P 0 ois trans 0, 1. 82 0. 3 18. 5 +15 18 9. 5 Predominantly 1, 4 trans 0.91 1. 82 0. 5 100 20. 4 +15 18 8. 4 Predominantly 1, 4 trans 1.09 1.82 0.6 100 20.4 +5 19 47 94.6 0.5 4.9 94 1.27 1. 82 0.7 100 20.4 +15 19 76.5 95.8 0 0.4 as 87 1. 40 1. 82 0.8 100 20.4 +15 18 57.5 95.8 0 0.5 3.7 as 1.82 1. s2 1 100 20.4 +15 18 13.2 56.9 38.4 0.3 4.4 as

(m) Molecular weight in toluene at +30 C.=.68.10

3 Example 7 Diphenyl-amino-alane was prepared by a method analogous to that described in literature for the prepara- 4 Example 9 The preceding test is repeated increasing the amount of tion of diethyl-amino-alane.

We reacted diphenyl amine dissolved in benzene with 5 on, NAlHq A1H .N(CH in molar ratio 1:1 and measuring the CHrCH, hydrogen developed in the reaction. H th f n The solution is evaporated under vacuum and the dry ence a recipe 15 as solid substance is weighed. This was reacted with a Benzene100 ml. benzoic solution of TiCl The catalyst system employed 0 TiCl -1.82 millimoles therefore is CHPCH,

AIHZ'N(CGH5)Z+TICI4 CH: NAlHz-LZS millimoles The recipe employed in these tests is as follows: CH CH Benzene 100 ml.; TiCl 1.82 millimoles; AlI-I N(C H z 1.09 millimoles; Al/Ti molar ratio 0.6:1; isoprene 1 /Ti molar i 7 20.4 g.; polymerization temperature +15 C. 1 4

After 16 hours the bottle is opened and the polymer Polymerization +15 is coagulated with methyl alcohol.

There are obtained 3 g. of gummy polymer which on 20 After 16 hours the poiymer 1s coagulated dned and LR. analysis showed the following structure: 96.1% Welghed' There are Obtauled (81%).ofp01ymer 1,4-cis structure; 1,4-trans structure absent; 0.4% 1-2; of gummy appearance whlch on 1 analysls Shows the 35% total unsaturation=87% fOllOWlIlg structure: 95.3% 1,4-c1s structure; 1,4-trans structure absent; 0.6% 1-2; 4.1%; total unsatura- Example 8 tion=88%. The compound E I 10 CH2CH2 I 1 E i? h 1 t h soprene is po ymerize uslng t e cata ytic sys em wit NAIH: the Al/Ti in molar ratios given below.

GHPCH The quantities employed are: was prepared by reacting a benzenic solution of piperi- Benzene loo ml dine with a benzenic solution of A1H .N(CH in molar Titanium tetrachloride 4 55 millimoles ratio 1:1. The hydrogen developed was collected and 4 AH (C H O 182 x'niuimoles measured (1 mole). The benzenic solution was evapoz 5 2 rated under vacuum to eliminate the solvent and the dry ISO solid is weighed. This is reacted with a benzenic soluratio 4 tion of TiCl Hence the catalytic system is formed of:

CH A white powdery polymer insoluble in benzene is obtamed 1n 43% y1eld. NAIH' T1014 Infrared analysis shows that it is predominantly 1-4 CHrCH: trans polyisoprene.

In a further advantageous aspect the invention comand the reclpe Is as follows prises the use of hydrides and halohydrides of aluminum BnZene100 complexed with tertiary amines, as cocatalysts. Comr- 11111111110165 pounds of this kind are for instance: All-I Cl.N(C H 45 Examples 11-15 HMIN CHPOmmunmole In the following polymerization tests the aluminum Olga-CH1 hydride complexed with trimethyl amine is replaced by Al/Ti molar ratio-0.521 monochloro-aluminum dihydride complexed with triethyl Isoprene-20.4 g. amine. The catalyst system, therefore, is formed of Polymerization temperature-+15 C. AlH Cl.N(C H and TiCl The catalyst is prepared in bottles as described herein- After 16 hours the content of the bottle is discharged before, into methyl alcohol and little polymer is obtained having In the following Table 2 are tabulated the conditions powdery appearance and giving LR. analysis result of of polymerization, the yields of solid polymer and the being predominantly 1.4-trans structure. infrared (IR) analyses.

TABLE 2 LR. Analyses, percent A1H2C1.N(C2H5)J T1014, Molar Solvent Isoprene, Dura Yield, Unsat. Examples mMoles mMoles ratio (Benzene), gr. ,C. tion, percent, Total Al/Ti (2111. hours 1,4 1,4 1-2 3-4 cis trans 0. 91 1. 82 0. 5 100 20. 4 +15 64 1 Predominantly 1, 4 trans 1. 09 1. 82 0.0 100 20.4 +15 40 85.5 96.3 0 0.4 3.3 1.28 1. a2 0.7 100 20.4 +15 17 63 95.1 0 0.5 4.5 87 1.46 1.82 0.8 100 20.4 +15 17 a4 0 0.3 4.7 90 1.64 1. 82 0.9 20.4 7 +15 64 20 88.4 6.7 0.3 4.6 87

(111) Molecular weight in toluene at 30 C.=5.5.10

wherein X is a member chosen from the group consisting of a halogen, a residue of a secondary amine, and a residue of a piperidine ring.

2. A process for the stereospecific polymerization of isoprene in the presence of a catalytic system consisting of titanium tetrachloride and of an aluminum compound in which the aluminum compound is a hydride of the general formula:

AlH X.Z

wherein X is a halogen, and Z is a complexing agent chosen from the group consisting of amines and ethers.

3. A process according to claim 2 wherein the aluminum compound is:

AlII C1.N(C H 4. A process according to claim 1 wherein the aluminum compound is chosen among the group consisting of:

and

CHfl-C I AIHQN /CH:

CHr-CH:

References Cited by the Examiner UNITED STATES PATENTS 2,921,057 1/1960 Mertzweiller 26093.7 2,977,349 3/1961 Brockway et a1. 26094.3 2,979,488 4/1961 Carpenter 26094.3

FOREIGN PATENTS 799,823 8/1958 Great Britain. 880,998 11/1961 Great Britain. 1,212,108 10/1959 France.

JOSEPH L. SCHOFER, Primary Examiner.

25 W. HOOVER, E. I SMITH, Assistant Examiners. 

1. A PROCESS FOR THE STEREOSPECIFIC POLYMERIZATION OF ISOPRENE IN SUBSTANTIALLY ANHYDROUS CONDITIONS IN THE PRESENCE OF A CATALYTIC SYSTEM CONSISTING OF TITANIUM TETRACHLORIDE ANDN ALUMINUM COMPOUND IN WHICH THE ALUMINUM COMPOUND IS AN ALUMINUM HYDRIDE OF THE FOLLOWING GENERAL FORMULA: 